| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_conv_fast_opt_q15.c |
| * Description: Fast Q15 Convolution |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the License); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "arm_math.h" |
| |
| /** |
| @ingroup groupFilters |
| */ |
| |
| /** |
| @addtogroup Conv |
| @{ |
| */ |
| |
| /** |
| @brief Convolution of Q15 sequences (fast version). |
| @param[in] pSrcA points to the first input sequence |
| @param[in] srcALen length of the first input sequence |
| @param[in] pSrcB points to the second input sequence |
| @param[in] srcBLen length of the second input sequence |
| @param[out] pDst points to the location where the output result is written. Length srcALen+srcBLen-1 |
| @param[in] pScratch1 points to scratch buffer of size max(srcALen, srcBLen) + 2*min(srcALen, srcBLen) - 2 |
| @param[in] pScratch2 points to scratch buffer of size min(srcALen, srcBLen |
| @return none |
| |
| @par Scaling and Overflow Behavior |
| This fast version uses a 32-bit accumulator with 2.30 format. |
| The accumulator maintains full precision of the intermediate multiplication results |
| but provides only a single guard bit. There is no saturation on intermediate additions. |
| Thus, if the accumulator overflows it wraps around and distorts the result. |
| The input signals should be scaled down to avoid intermediate overflows. |
| Scale down the inputs by log2(min(srcALen, srcBLen)) (log2 is read as log to the base 2) times to avoid overflows, |
| as maximum of min(srcALen, srcBLen) number of additions are carried internally. |
| The 2.30 accumulator is right shifted by 15 bits and then saturated to 1.15 format to yield the final result. |
| |
| @remark |
| Refer to \ref arm_conv_q15() for a slower implementation of this function which uses 64-bit accumulation to avoid wrap around distortion. |
| */ |
| |
| void arm_conv_fast_opt_q15( |
| const q15_t * pSrcA, |
| uint32_t srcALen, |
| const q15_t * pSrcB, |
| uint32_t srcBLen, |
| q15_t * pDst, |
| q15_t * pScratch1, |
| q15_t * pScratch2) |
| { |
| q31_t acc0; /* Accumulators */ |
| const q15_t *pIn1; /* InputA pointer */ |
| const q15_t *pIn2; /* InputB pointer */ |
| q15_t *pOut = pDst; /* Output pointer */ |
| q15_t *pScr1 = pScratch1; /* Temporary pointer for scratch1 */ |
| q15_t *pScr2 = pScratch2; /* Temporary pointer for scratch1 */ |
| const q15_t *px; /* Intermediate inputA pointer */ |
| q15_t *py; /* Intermediate inputB pointer */ |
| uint32_t j, k, blkCnt; /* Loop counter */ |
| uint32_t tapCnt; /* Loop count */ |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| q31_t acc1, acc2, acc3; /* Accumulators */ |
| q31_t x1, x2, x3; /* Temporary variables to hold state and coefficient values */ |
| q31_t y1, y2; /* State variables */ |
| #endif |
| |
| |
| /* The algorithm implementation is based on the lengths of the inputs. */ |
| /* srcB is always made to slide across srcA. */ |
| /* So srcBLen is always considered as shorter or equal to srcALen */ |
| if (srcALen >= srcBLen) |
| { |
| /* Initialization of inputA pointer */ |
| pIn1 = pSrcA; |
| |
| /* Initialization of inputB pointer */ |
| pIn2 = pSrcB; |
| } |
| else |
| { |
| /* Initialization of inputA pointer */ |
| pIn1 = pSrcB; |
| |
| /* Initialization of inputB pointer */ |
| pIn2 = pSrcA; |
| |
| /* srcBLen is always considered as shorter or equal to srcALen */ |
| j = srcBLen; |
| srcBLen = srcALen; |
| srcALen = j; |
| } |
| |
| /* Pointer to take end of scratch2 buffer */ |
| pScr2 = pScratch2 + srcBLen - 1; |
| |
| /* points to smaller length sequence */ |
| px = pIn2; |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| k = srcBLen >> 2U; |
| |
| /* Copy smaller length input sequence in reverse order into second scratch buffer */ |
| while (k > 0U) |
| { |
| /* copy second buffer in reversal manner */ |
| *pScr2-- = *px++; |
| *pScr2-- = *px++; |
| *pScr2-- = *px++; |
| *pScr2-- = *px++; |
| |
| /* Decrement loop counter */ |
| k--; |
| } |
| |
| /* Loop unrolling: Compute remaining outputs */ |
| k = srcBLen % 0x4U; |
| |
| #else |
| |
| /* Initialize k with number of samples */ |
| k = srcBLen; |
| |
| #endif /* #if defined (ARM_MATH_LOOPUNROLL) */ |
| |
| while (k > 0U) |
| { |
| /* copy second buffer in reversal manner for remaining samples */ |
| *pScr2-- = *px++; |
| |
| /* Decrement loop counter */ |
| k--; |
| } |
| |
| /* Initialze temporary scratch pointer */ |
| pScr1 = pScratch1; |
| |
| /* Assuming scratch1 buffer is aligned by 32-bit */ |
| /* Fill (srcBLen - 1U) zeros in scratch1 buffer */ |
| arm_fill_q15(0, pScr1, (srcBLen - 1U)); |
| |
| /* Update temporary scratch pointer */ |
| pScr1 += (srcBLen - 1U); |
| |
| /* Copy bigger length sequence(srcALen) samples in scratch1 buffer */ |
| |
| /* Copy (srcALen) samples in scratch buffer */ |
| arm_copy_q15(pIn1, pScr1, srcALen); |
| |
| /* Update pointers */ |
| pScr1 += srcALen; |
| |
| |
| /* Fill (srcBLen - 1U) zeros at end of scratch buffer */ |
| arm_fill_q15(0, pScr1, (srcBLen - 1U)); |
| |
| /* Update pointer */ |
| pScr1 += (srcBLen - 1U); |
| |
| /* Temporary pointer for scratch2 */ |
| py = pScratch2; |
| |
| |
| /* Initialization of pIn2 pointer */ |
| pIn2 = py; |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = (srcALen + srcBLen - 1U) >> 2; |
| |
| while (blkCnt > 0) |
| { |
| /* Initialze temporary scratch pointer as scratch1 */ |
| pScr1 = pScratch1; |
| |
| /* Clear Accumlators */ |
| acc0 = 0; |
| acc1 = 0; |
| acc2 = 0; |
| acc3 = 0; |
| |
| /* Read two samples from scratch1 buffer */ |
| x1 = read_q15x2_ia (&pScr1); |
| |
| /* Read next two samples from scratch1 buffer */ |
| x2 = read_q15x2_ia (&pScr1); |
| |
| tapCnt = (srcBLen) >> 2U; |
| |
| while (tapCnt > 0U) |
| { |
| |
| /* Read four samples from smaller buffer */ |
| y1 = read_q15x2_ia ((q15_t **) &pIn2); |
| y2 = read_q15x2_ia ((q15_t **) &pIn2); |
| |
| /* multiply and accumlate */ |
| acc0 = __SMLAD(x1, y1, acc0); |
| acc2 = __SMLAD(x2, y1, acc2); |
| |
| /* pack input data */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| x3 = __PKHBT(x2, x1, 0); |
| #else |
| x3 = __PKHBT(x1, x2, 0); |
| #endif |
| |
| /* multiply and accumlate */ |
| acc1 = __SMLADX(x3, y1, acc1); |
| |
| /* Read next two samples from scratch1 buffer */ |
| x1 = read_q15x2_ia (&pScr1); |
| |
| /* multiply and accumlate */ |
| acc0 = __SMLAD(x2, y2, acc0); |
| acc2 = __SMLAD(x1, y2, acc2); |
| |
| /* pack input data */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| x3 = __PKHBT(x1, x2, 0); |
| #else |
| x3 = __PKHBT(x2, x1, 0); |
| #endif |
| |
| acc3 = __SMLADX(x3, y1, acc3); |
| acc1 = __SMLADX(x3, y2, acc1); |
| |
| x2 = read_q15x2_ia (&pScr1); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| x3 = __PKHBT(x2, x1, 0); |
| #else |
| x3 = __PKHBT(x1, x2, 0); |
| #endif |
| |
| acc3 = __SMLADX(x3, y2, acc3); |
| |
| /* Decrement loop counter */ |
| tapCnt--; |
| } |
| |
| /* Update scratch pointer for remaining samples of smaller length sequence */ |
| pScr1 -= 4U; |
| |
| /* apply same above for remaining samples of smaller length sequence */ |
| tapCnt = (srcBLen) & 3U; |
| |
| while (tapCnt > 0U) |
| { |
| /* accumlate the results */ |
| acc0 += (*pScr1++ * *pIn2); |
| acc1 += (*pScr1++ * *pIn2); |
| acc2 += (*pScr1++ * *pIn2); |
| acc3 += (*pScr1++ * *pIn2++); |
| |
| pScr1 -= 3U; |
| |
| /* Decrement loop counter */ |
| tapCnt--; |
| } |
| |
| blkCnt--; |
| |
| /* Store the results in the accumulators in the destination buffer. */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| write_q15x2_ia (&pOut, __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16)); |
| write_q15x2_ia (&pOut, __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16)); |
| #else |
| write_q15x2_ia (&pOut, __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16)); |
| write_q15x2_ia (&pOut, __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16)); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* Initialization of inputB pointer */ |
| pIn2 = py; |
| |
| pScratch1 += 4U; |
| } |
| |
| /* Loop unrolling: Compute remaining outputs */ |
| blkCnt = (srcALen + srcBLen - 1U) & 0x3; |
| |
| #else |
| |
| /* Initialize blkCnt with number of samples */ |
| blkCnt = (srcALen + srcBLen - 1U); |
| |
| #endif /* #if defined (ARM_MATH_LOOPUNROLL) */ |
| |
| /* Calculate convolution for remaining samples of Bigger length sequence */ |
| while (blkCnt > 0) |
| { |
| /* Initialze temporary scratch pointer as scratch1 */ |
| pScr1 = pScratch1; |
| |
| /* Clear Accumlators */ |
| acc0 = 0; |
| |
| tapCnt = (srcBLen) >> 1U; |
| |
| while (tapCnt > 0U) |
| { |
| |
| /* Read next two samples from scratch1 buffer */ |
| acc0 += (*pScr1++ * *pIn2++); |
| acc0 += (*pScr1++ * *pIn2++); |
| |
| /* Decrement loop counter */ |
| tapCnt--; |
| } |
| |
| tapCnt = (srcBLen) & 1U; |
| |
| /* apply same above for remaining samples of smaller length sequence */ |
| while (tapCnt > 0U) |
| { |
| |
| /* accumlate the results */ |
| acc0 += (*pScr1++ * *pIn2++); |
| |
| /* Decrement loop counter */ |
| tapCnt--; |
| } |
| |
| blkCnt--; |
| |
| /* The result is in 2.30 format. Convert to 1.15 with saturation. |
| Then store the output in the destination buffer. */ |
| *pOut++ = (q15_t) (__SSAT((acc0 >> 15), 16)); |
| |
| /* Initialization of inputB pointer */ |
| pIn2 = py; |
| |
| pScratch1 += 1U; |
| } |
| |
| } |
| |
| /** |
| @} end of Conv group |
| */ |